This invention relates to articles having a multi-layer decorative and protective coating thereon.
It is currently the practice with various articles, such as for example, brass or zinc articles, such as faucets, faucet escutcheons, door knobs, door handles, door escutcheons and the like to first buff and polish the surface of the article to a high gloss and to then apply a protective organic coating, such as one comprised of acrylics, urethanes, epoxies, and the like, onto this polished surface. This system has the drawback that the buffing and polishing operation, particularly if the article is of a complex shape, is labor intensive. Also, the known organic coatings are not always as durable as desired, and are susceptible to attack by acids. It would, therefore, be quite advantageous if articles, such as for example, brass or zinc articles, or indeed other articles, could be provided with a coating which provided the article a decorative appearance such as, for example, that of highly polished brass, provided wear resistance and corrosion protection, and also provided improved chemical resistance. The present invention provides such a coating.
The present invention is directed to an article, such as a plastic, ceramic, or metallic article, preferably a metallic article, having a multi-layer coating on at least a portion of its surface. More particularly, it is directed to an article or substrate, particularly a metallic article such as stainless steel, aluminum, brass or zinc, having deposited on its surface multiple superposed layers of certain specific types of materials. The coating is decorative and also provides corrosion resistance, wear resistance and improved resistance to chemicals, such as acids. In one embodiment the coating provides the appearance of highly polished brass, i.e., has a brass color tone, while in another embodiment it provides the color of chrome.
The article has deposited on its surface a polymeric base coat layer. The polymeric base coat layer functions to level the surface of the article, cover any scratches or imperfections in the surface of the article, and provide a smooth and even surface for the deposition of the subsequent layers of the multi-layered coating.
In one embodiment over the polymeric base coat layer is applied, by vapor deposition, a chromium adhesion promoting layer. Over the chromium adhesion promoting layer is deposited a relatively thick strengthening layer comprised of chromium compound. Over the strengthening layer is deposited a color layer comprised of a metal such as chromium, stainless steel, refractory metal, etc., or of a reacted metal compound such as zirconium nitride, titanium nitride, zirconium-titanium alloy nitride, and the like. In another embodiment the chromium adhesion promoting layer is absent and the chromium compound strengthening layer is deposited directly onto the polymeric base coating layer.
In another embodiment disposed over the color layer is a transparent protective layer comprised of a metal oxide or metal alloy oxide or, the reaction products of (a) metal or metal alloy, (b) oxygen, and (c) nitrogen. This transparent, protective layer provides improved chemical resistance, such as improved resistance to acids and bases, and improved corrosion resistance.